Telephone-exchange apparatus



(No Model.) 2 Sheets-Sheet 1.

P. G. BEACH. TELEPHONE EXGHANGE APPARATUS.

No. 447,485. Patented Mar. 3, 1891.

(No Model.) 2 Sheets-Sheet 2.

P. G. BEACH. TELEPHONE EXCHANGE APPARATUS;

My l

Patented Mar. 3, 189-1,

NrrE I STATES FRANKLIN G. BEACH, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE AMERICAN BELL TELEPHONE COMPANY,

OF BOSTON, MASSACHUSETTS.

TELEPHONE-EXCHANGE APPARATUS.

SPECIFICATION forming part of Letters Patent No. 447,485, dated March 3, 1891. Application filed February 4, 1888. Serial No. 262,966. (No model.)

erence being had to the accompanying drawro ings, forming a part of this specification.

My invention relates to a telephone-exchange system in which the lines are run inv pairs, each line of every pair beluga single. circuit. Each line of every pair may have.

upon it one subscribers station, which can signal to or receive a signal from the central office independent of the station located on the second line of the same pair. Vhen the subscriber at either station removes his telephone from the automatic switch, the two lines of the pair are disconnected from ground and automatically connected together and make a metallic circuit for talking purposes, the object of such metallic circuits for talking 2 5 being to overcome inductive disturbances, the

v advantage of which over single circuits is generally understood by persons skilled in the business. 1

My invention consists more especially in the circuits and switching apparatus at the station of each subscriber and at the central office. Any two subscribers stations conveniently located upon or near the same route may be connected witha pair of lines, one

3 5 station upon each line of each pair.

By the use of myinvention in a telephoneeXchange single lines can be utilized for metallic circuits without the necessity of furnishing additional wires for the return-cir- ,in the usual manner. of themetallic circuit terminates in'the in turned to the right or left.

paired lines forming a metallic circuit when the said two lines are substantially equidistant from any and all other adjacent and parallel lines. The two lines of each pair are connected with the same spring-jack switch on the switch-board, one line being connected to the spring or lever and the other to the frame or body of the spring-jack. The circuit of the line connecting with the spring passes through the spring and its contactpoint to an annunciator, and thence to ground The other line or limb sulated frameofwthe jack.

The apparatus at the different subscribers stations is arranged so that in signaling both subscribers of the pair use a portion of the same line of the circuit, throwing down the same shutter at the central station. The oporator at the central station, seeing a shutter fall, inserts a loop-plug in the corresponding switch and at the same time loops her telephone into the circuit of the cords of the loop-plug. She is thus placed in communication with the subscriber, Whoever it may be, who has sent in the signal. Polarized bells adapted to respondto a straight intermittent current in one direction only are provided at the subscribers stations, and the generators at the different stations are preferably adapted to send current in one direction or the other, accordingly as they are 7 The source of electricity at the central orifice may be a 8 5 power-generator constructed to send alternating currents or current in reversals or a battery with a pole-changer in circuit. I am thus enabled to prevent false signals at the subscribersstations when the clearing-out sig- 9o nal is sent, as will be hereinafter described.

As an additional precaution against false signals, I provide for either opening the circuit or for closing the circuit to ground at the central office by the falling of the shutter of 5 the clearingout annunciator.

By means of suitable connections with the generator or signaling-battery'at the. central office I am enabled to call up either one of a pair of subscribers without disturbing the OllllBl My invention will be understmd by reference to the accompanying drawings, in which- Figure 1 is a diagram illustrative of a pair of subscribers stations connected with a switch at the central office and the key-board and signaling apparatus of the switch-board. Fig. 2 is a detail view showing the operation of the telephone-switch at a subscribers station. Fig. 3 is a View showing the operation of the loop-switch of the key-board apparatus. Fig. 1L is a detail sectional view of a loop-plug provided with a divided metallic heel, one division of the heel being connected with the tip of the plug and the other division being connected with the insulated metallic sleeve upon the shank of the plug. Fig. 5 is a plan of the metallic heel of the plug. Fig. 6 is a detail sectional view of a clearing out annunciator for opening the circuit by the falling of the shutter. Figs. 7 and 8 are rear and sectional views, respectively, of a clearing-out annunciator closing the line to ground when the shutter falls.

Like parts are indicated by similar letters and figures of reference throughout the diferent figures.

The spring-jack switch, the loop-plug, and the loop-switch are old in the art, and therefore require no special description. The telephoneswitch is in mode of operation similar to the telephone-switch described in United States Letters Patent No. 371,260, granted \Villiam M. Goodridge, October 11, 1887.

At the subscribers station No. 9 I have shown the'usual telephone a, transmitter 1), bell c, and generator cl. At station No. 9 I have shown also a telephone a, a transmitter 1), bell c, and generator d. Beginning at ground at station 9, the circuit of the line f may be traced through the generator d, hell 0, and spring g to plate 2 and thence to the contact-spring g of station 9, thence to plate 2', and thence to key h at said station, and thence to the spring of springacki upon the switchboard through the contact of said spring-jack switch, and thence through an annunciator 9 to ground. Beginning at ground at station 9, the circuit of limbl maybe traced to spring m and plate at of the telephone-switch and thence to station 9, where it passes through bell c, the generator cl, and spring on to plate n, and thence to key 0, and thence to the insulated frame of spring-jack Branch Z is thus normally open at spring-jack i. This is the normal circuit of the lines or limbs Z and f when the telephones a and a are hung upon the switch-levers, as illustrated in Fig. 2, in which position the three springs on one side of the rubber heel are lifted from plates e 71., while the springs g m are allowed to close upon plates 6 72, respectively. On removing the telephone from the switch the three springs, pressing in one direction against the rubber heel upon the short arm of the lever of the telephone-support, will close upon their opposing contacts and force the'springs g m away from their contacts.

I will now describe the manner of sending a signal from station 9 to the central ofiice, the manner of receiving the call at the central office, and connecting and disconnecting the different stations.

Suppose subscriber 9 wishes a connection. He turns his generator d, sending current over linefto annunciator 9, and thereupon takes down his telephone a, thus bringing the telephone into circuit, the ground terminals of both limbs of said circuit being at the same time disconnected as springs g m are lifted from their normal contacts e and n, respectively. The operator at the central ofiice, seeing shutter 9 fall, atonce picks up plug 19 of her pair of plugs and inserts said plug into spring-jack i. The tip of the plug is thus connected with the spring of the switch and the sleeve of the plug with the frame. Thus lines f Z are looped together in metallic circuit, and the lever q of the loop-switch being thrown over to the position'shown brings the telephone 7' into this circuit.

I will now trace the metallic circuit between the subscribers telephoned at station 9 and the operators telephone 7' at the central office. Beginning at the tip of plug 19, the circuit may be traced through strand 3 of the cord to a plate of the loop-switch, and thence through the telephone a", Fig. 3, and after passing through the loop-switch the circuit may be traced by wire 5" to the tip of plug t. The heel of plug t rests upon a metallic support, and hence a connection is established between the different contacts or points of plug t. Thus the circuit may be traced through the strand it, which connects the sleeves of the two plugs to the frame of switch i, and thence by wire Z through key 0, plate 72', and spring m at station 9" to the plate n of the switch at station 9, and thence through spring 0:, telephone a, and spring to to the terminal plate 6 of the telephone-switch, and thence by linef, as heretofore traced, to the spring of switch '6, and thence to the tip of plugp, thus completing the metallic circuit. Subscriber at station 9", in order to signal, presses first upon push-key 0, forcing said key away from its normal contact and closingsaid keyo upon key It and separating said key h from its normal contact. Subscriber 9 thus brings his generator cl into connection with the portion of linefleading to the annunciator 9 at the central office, and while holding down said push-key 0 sends current to the central oflice. The signal-current of subscriber 9 is thus sent from ground at station 9 over line Z to key 0, and thence from key h over line f to the central oifice. The operator, seeing the shutter fall, inserts plug 19, as before described with respect to subscriber 9", and the same connections are formed at the central ofiice. The circuits at stations 9 and 9 will be different, however. Subscriber 9 having signaled, allows keys h an d 0 to resume their positions, as shown, and at once takes down his telephone, thus opening connections of springs g m and closing telephone connections o w. Telephone a is thus included in a metallic circuit, which may be traced at station 9 as follows: From key 0 to plate or terminal n, thence to telephone-spring t", and thence through tele phone a to the other telephone-spring w, and thence to plate 6, and thence, as indicated by line f, to key It. Thus telephone a is looped into a metallic circuit with the operators telephone 1' when the telephone a is off the switch and plug 19 is inserted in spring-jack t. The operator having learned the subscriber wanted, inserts plug 25 into the proper spring-jack and presses on the proper key to throw-current from the signal battery or generator to the particular subscriber asked for. Any key-board apparatus may be used for this purpose. I have shown keys y y for throwing current to the tip of either plug and the keys .2 z. for throwing current to the sleeve of either plug.

It will be understood, as shown in Fig. 4, that strand 3 connects with the tip of the plug and strand u with the sleeve of the plug.

It is seen from the foregoing description that either station of any pair can obtain connection at the central office independent of and without ringing the bell at the other station upon the same pair of lines.

After two subscribers are connected, the clearing-out annunciator 15 may be included in the circuit by simply throwing lever q of the listening-key to its other position. Either subscriber may thus clear out by sending current to line. In case current were sent to clear out through the annunciator i and connections over line f to station 9 the circuit would be completed through bell c at station 9 if the telephone a at station 9 were upon its support. Bell 0, being polarized, would not respond. I

In the same telephone-exchange it is often desirable to use different kinds of electric current, as straight current, intermittent currents, and current sent in reversals. It is therefore desirable not to depend entirely upon polarized bells for preventing false signals at station 9. This I accomplish either by opening or by grounding the line by the falling of the clearing-out shutter. The clearing-out annunciator t, Fig. 1, (for detail see Fig. (5,) is constructed so that when the shutter falls its weight or momentum acquired in falling serves to separate spring 25 from its normal contact, thus opening the line at the point of said contact. I have shown an eccentric piece upon the lower part of the shutter which is forced against a spring t, resting upon a loose pin of insulating material when the shutter falls. The pin, being thus forced back, serves to lift spring 6', thus opening the circuit. Instead of opening the circuit, a third leg-connection may be closed directly to ground, as shown in Figs. 7 and'ti. The connection 15 of the line is extended, so that when the shutter falls and spring 29 is forced back it will close upon contact t. It will be understood that the plate 25 of the annunciator is connected to ground, and hence a direct ground connection is provided when spring 25 closes upon contact i Bell 0, even if not polarized, could therefore give no signal after the falling of the shutter.

I have thus described my invention without reference to the manner of signaling and making connection between the two stations of a given pair of subscribers.

This feature of my invention I will now describe, it being understood that the principal feature of my invention is not to be considered as in any way limited or restricted by the particular mode of making connections between the two stations of a pair, since this may be accomplished in several different ways in connection with my metallic circuit system.

At station 9 I have shown a push-key 1,

mounted upon two contact springs or keys 2 In my previous description I have disregarded these springs and their connections, since they are normally included in the circuits f and Z, respectively, and have no special function as keys, except when used for making connections between stations 9 and 9". Suppose now the subscriber at station 9 wishes to make connection with station 9.

-He presses upon key 1 with one hand, sepaand thence, as heretofore traced, through the.

bell c at station 9. Having thus signaled subscriber 9, subscriber 9 lets go the generator and takes down his telephone a. Subscriber 9 having also taken down his telephone and subscriber 9 still holding key 1 depressed, the pair of subscribers 9 and 9 will be connected together in metallic circuit. This metallic circuit through telephones CL and a may be traced as follows: from plate n to spring 1*, telephone a, spring to, and

plate 6, thence to key 2, and thence by wire I 4 to spring m, and thence to plate 11 of the switch at station 9, thence by springo through telephone a to spring to, thence to plate e, and thence back to spring g at station 9 and thence by wire 5 to spring 3, and thence to plate 71, thus completing the metallic circuit between the two subscribers 9 and 9 Subscriber 9 may thus without assistance from the central office communicate with subscriber 9.

It will be understood that when keyl is depressed the portions of wires f Z leading to the central office are cut off at springs 2 and 3.

Then subscriber at station 9 wishes connection with station 9", he calls up the central ot'fice and gives his order and the operator thereupon calls up station 9" and directs the subscriber at station 9 to connect with station 9, which he does by simply depressing keys 2 and 3, as before described. At station 9",l have shown the coils of the hell 0' connected in multiple are, in order that the resistance of the coils when included in the talking-circuit may be as low as possible. I preferably thus connect the coils of all the bells and annunciators in multiple arc. The single circuit 10 is shown passing through its switch It and its annunciator 10 to ground. The frame of switch 7 is shown connected by wire it directly to ground. Thus it appears that any subscriber 9 or 9" maybe connected with any subscriber 10 having a single circuit.

Either of two subscribers of a pair may be connected in metallic circuit with either subscriber of any other pair of the exchange without interfering with or disturbing either of the other subscribers of the two pairsthat is to say, subscriber t) of the outer station may tall; with any subscriber of the exchange without disturbing the intermediate subscriber t)", or any other subscriber except the particular one called for, and subscriber it" may talk with any other subscriber of the exchange without disturbing subscriber 9 or any other one except the particular one wanted.

My system as thus described enables me to group the single lines in such manner that the subscribers may each be provided with complete metallic circuits for talking without materially increasing the expense for wire over and above the expense of single circuit-lines, and at the same time the switchboard apparatus is very materially reduced, which latter saving in the case of multipleswitch-board systems would be very large.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. The combination, with two telephone-exchange stations, of two lines, each passing through each of said stations and each to ground at one of said stations, said lines extending to the central office and being there connected with dilterent portions of the same spring-jack, oneof said portions of the springjack being connected through an annunciatorto ground and the other portion being normally insulated, and switching apparatus and generators at the dilterent stations, whereby either subscriber may send current through said annunciator at the central ofiice, substantially as described.

2. The con'ibination, with two telephonelines, each connected with different portions of the same switching device at the central otiice and extending through each of said stations and to a separate ground at one of said stations, of telephones, one at each of said stations and oneat the centralot'tice, and switching apparatus at each of said stations and at the central ofliee, whereby said lines may be disconnected from ground and the telephone at either station looped in metallic circuit with the telephone at the central office.

3. The combination, with two subscribers stations, of two lines grounded at one of said stations and passing, respectively, through both of said stations in series to a common switching device at the central office, one of said lines being closed through an annunciator to ground and the other being normally open at the central ofiice, of the generator of the subscriber at the intermediate station included in the normally-open line, and a switching device for closing said generator to the closed line, whereby the subscriber at the said intermediate station may send current from his generator to operate the annunciator included in the circuit grounded at the central ot'fice.

4 The combination, with two electric circuits passing each in series through an outer station and an intermediate station to the central oflice, one of said circuits being normally open and the other being normally grounded through an annunciator at the central office, and both of said circuits being normally grounded at the outer station, of the generator of the intermediate station included in the normally-open circuit, and switching apparatus for connecting said generator to the circuit including the annunciator.

5. Two electric circuits passing each from a separate ground connection at one subscribers station through said station and another intermediate subscribers station to the central-office switch-board of a telephoneexchange, one of said lines being normally open at said switch-board and the other passing from said switch-board through an annunciator to ground, of the generator and bell of the different stations, the bell and generator at one station being in one line and the bell and generator of the other station being in the other line, and switching apparatus at the intermediate station, where by current may be sent from either station to operate the ann unciator at the central oflice without ringing. the bell of the other station.

(5. Two telephone-lines extending through stations 9 I)" normally to the central otiice, said lines being normally grounded at station 9, in combination with switching apparatus at station 0 for disconnecting both of said lines from the central office and uniting them in a circuit including the signal dcvicesthat is, the bell and generator of each station and automatic telephone-switches, one at each station, and the said subscribers telephones, whereby current may be sent from the generator at station 9 to ring the bell at station 9, and whereby on taking down the telephones said telephones will be connected in metallic circuit while the signal devices of stalion 9 are disconnected therefrom.

7. The combination, with two lines connected with diflercnt parts of the same switch at the central office, and each line including the bell of a different subscribers station, of aplug with two points or contacts for con-,

necting with the different parts of said switch,

- respectively, and the strands of the cord of said plug, a key in each strand, and a source of electricity whereby current may be sent from the central office to signal the subscriber at either of the stations.

8. The combination, with the operators telephone at the central office, of flexible conducting-strands and a loopplug connected therewith, a loop-switch for bringing the telephone into the circuit of the cords and a switch upon the switch-board, with which two different lines are connected, each line passing through a station 9 to a station 9 and to ground, and the polarized bells at said stations included, respectively, in diiterent lines, and a source of electricity for sending current in reversals and keys for closing said source of electricity to either line, whereby the operators telephone may be looped into a metallic circuit formed between the two lines, or whereby current may be sent to ring the bell at either station at the will of the operator.

9. The combination, with two subscribers stations, of two lines grounded at one of said stations and passing, respectively, through both of said stations in series to a common switching device at the central office, one of said lines being closed through an annuneiator to ground and the other being normally open at the central office, the generator of the subscriber at the intermediate station being included in the normall -open line with a switching device for closing said generator to the closed line, whereby the subscriber at the said intermediate station may send current from his generator to operate the annuciator included in the circuit grounded at the central oflice.

10. The combination, substantially as specified, of two parallel telephone-lines extending between a central station, an intermediate substation, and a terminal sub-station and connected to earth at the latter, signaling appliances at each sub-station, included each in the circuit of one of the said lines, switching devices at each sub-station controlling the outgoing and incoming ends of both lines, 0perated in one direction by a positive force to unite the two ends of the said two lines leading to the central station and to form thereby a metallic talking-circuit, and oppositely, by the replacement of the telephone on its holder, acting against said positive force to break the said metallic circuit and to re-establish the two independent signaling-circuits, a common switching and signal-receiving appliance at the central station for both lines, and a circuit-changer at the intermediate sub-station, whereby the call-sending appliance at said station may be temporarily transferred from one signaling-line to the other, for the purposes described.

trolled by the removal and replacement of said telephone in its holder and being adapted when the said telephone is removed to disconnect the earth terminals aud to unite the central-station ends of both lines, thereby forming a metallic circuit including the substation telephones and extending from said sub-station to the central station, substantially as specified.

12. In combination with two subscribers.

stations connected with each other and with a central station by means of two electric lines, forming together a metallic or loop talking-circuit, and severally independent circuits, each including the signaling apparatus of one of the said substations, an automatic telephone-switch at each sub-station determining by its position the arrangement at any given moment of said two lines, a telephone at each sub-station, adapted for inclusion in the metallic talking-circuit and mechanically controlling the said automatic switch, an independent circuit-changer at the intermediate station only, acting in its normal position to maintain continuity of the two line-circuits, and two normally-discontinuous branches derived from the lines leading to the outer sub-station and extending to alternative contact-terminals of the said circuit-changer, the said circuit-changer being movable into contact therewith, and being thereby adapted to complete a metallic telephone-circuit between the two sub-stations independent of the central station.

13. In a telephone-exchange system, the combination of a central station, two sub-stations, signaling devices at each sub-station, two electric conducting-lines extending from the central station through the signaling appliances of the two sub-stations, respectively, to earth terminals at the outermost sub-station, thus constituting an independent signaling-circuit for each sub-station, and means, as indicated, at each sub-station for simultaneously disconnecting both lines from their earth-terminal extensions and for uniting the said two lines through the sub-station telephones for the purpose of forming a metallic talking-circuit, substantially as hereinbefore described.

14. In a telephone-exchange system, a 'central station, two sub-stations, two parallel earth return-lines constituting signal-receiving circuits for the said two sub-stations, respectively, and each passing through both sub-stations serially to ground at the outer most one, and switching devices capable of ITO two positions at each sub-station, which in In Witness whereof Iherennto subscribe my one position maintain continuity of the said name this 13th day of December, A. D. 1887. I0

two independent signaling-lines, but in another disconnect the ground terminal there- FRANKLIN G. BEACH.

from and unite the two ends of the portions l I of both lines leading to the central station, \Vitnesses:

thus constituting a metallic talking-circuit, CHAS. G. HAWLEY, substantially as specified. GEORGE P. BARTON. 

